The retinal pigment epithelium (RPE) of human eyes will be evaluated by electron microscopy for their content of melanin and lipofuscin in the macula as compared to non-macular areas of the retina. Data from various age groups will be compared. Possible factors contributing to the formation of lipofuscin will be examined using bovine RPE in vitro. Oxygen consumption during phagocytosis of latex beads will be assessed to see if there is a respiratory burst and whether H2O2 is formed.Methods will be worked out for obtaining isolated viable bovine RPE for purposes of testing for lipid peroxidation mechanisms in these cells.